Keady search my post for my overall on the stage 2
go with stage 2... with the GT i didn't find any difference in mpg between 1 and 2, if anything i may get better mpg with 2... the reason.. the car is swifter off the line.. I don't need to floor it off the line to get what i want from the car.....I didn't find a huge loss in MPG when i went Dinan in the first place and i think a lot of that has to do with the lighter foot the Dinan affords you to have....
Go for it you will be amazed..
BUT plan on then wanting to change your suspension even in sport the power of 500HP could use slightly stiffer springs...
And the difference the change of exhaust makes is mind blowing also... i did stage 1 then stage 2 and there was a noticeable difference, but when i switched to Eisenmann exhausted....holy s**t!!
Best thing is people just don't expect it from this big car....
hope this helps...
Keady i didn't notice your location before i went to reply but if your in the tristate area an want to check mine out feel free to PM me...
2012 GT 550ix Msport (feb12)(ok early march 12)
09 X5 4.8
12 X3 35i (the wife)
61 356 roadster